Who really needs a blood culture?

In this prospective observational cohort, researchers derived and validated a decision rule to predict true bacteremia in 3730 ED patients who had blood cultures drawn (abstract). They determined that patients should get a blood culture if they had at least 1 major or 2 minor criteria (Major criteria were temp>39.5, indwelling vascular catheter, or clinical suspicion of endocarditis; Minor criteria were temp 38.3-39.4, age >65, chills, vomiting, SBP<90, WBC>18, PMN>80%, bands>5%, platelets>150, or creatinine>2). Using these criteria in the validation set, the decision rule had a NPV of 99% (of patients without criteria, <1% actually had bacteremia), indicating its value in identifying those that DO NOT need a blood culture. However, it could not accurately identify those that DO need a blood culture (with a PPV of only 11%, a large number of patients with criteria would not be bacteremic).

Danielle Scheurer

Dr. Scheurer is a clinical hospitalist and the Medical Director of Quality and Safety at the Medical University of South Carolina in Charleston, South Carolina, and is Assistant Professor of Medicine. She is a graduate of the University of Tennessee College of Medicine, completed her residency at Duke University, and completed her Masters in Clinical Research at the Medical University of South Carolina. She also serves as the Web Editor and Physician Advisor for the Society of Hospital Medicine.

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